The Problem with Bookmarklets

Oct 13, 2025 by magicalceylontours.com 106 views

Introduction

When it comes to loading external JavaScript files, Chrome's Cross-Origin Read Blocking (CORB) feature can be a significant obstacle. CORB is designed to prevent malicious scripts from accessing sensitive data, but it can also block legitimate scripts from loading. In this article, we'll explore how to bypass Chrome's CORB feature using a bookmarklet.

Understanding CORB

CORB is a security feature implemented in Chrome to prevent cross-origin resource sharing (CORS) attacks. It blocks scripts from accessing data from other domains, even if the script is loaded from a different origin. This is done to prevent malicious scripts from accessing sensitive data, such as cookies or local storage.

The Problem with Bookmarklets

Bookmarklets are small JavaScript programs that can be saved as bookmarks in a web browser. They are often used to perform tasks such as loading external scripts or modifying web pages. However, when it comes to loading external JavaScript files, Chrome's CORB feature can block the script from loading.

The Issue with Creating a New Script Element

When creating a new script element using a bookmarklet, Chrome's CORB feature can block the script from loading. This is because the script element is created from a different origin, and Chrome's CORB feature prevents scripts from accessing data from other domains.

Bypassing CORB with a Bookmarklet

To bypass Chrome's CORB feature, we can use a bookmarklet to create a new script element and change the src attribute to our source code. However, we need to use a specific technique to bypass CORB.

Technique 1: Using the `eval()` Function

One way to bypass CORB is to use the eval() function to execute the script. The eval() function can execute a string as JavaScript code, which can bypass CORB.

javascript:(function(){var script=document.createElement('script');script.src='https://example.com/script.js';document.body.appendChild(script);eval(script.src);})();

Technique 2: Using the `fetch()` API

Another way to bypass CORB is to use the fetch() API to load the script. The fetch() API can load data from a different origin, which can bypass CORB.

javascript:(function(){fetch('https://example.com/script.js').then(response=>response.text()).then(data=>eval(data));})();

Technique 3: Using a Proxy Server

A third way to bypass CORB is to use a proxy server to load the script. A proxy server can act as an intermediary between the script and the web page, which can bypass CORB.

javascript:(function(){var proxy='https://example.com/proxy.php';fetch(proxy+'?url=https://example.com/script.js').then(response=>response.text()).then(data=>eval(data));})();

Conclusion

Bypassing Chrome's CORB feature can be a complex task, but it is possible using specific techniques. In this article, we've explored three techniques to bypass CORB using a bookmarklet: using the eval() function, using the fetch() API, and using a proxy server. By using these techniques, you can load external JavaScript files in Chrome, even if CORB is enabled.

Additional Tips and Tricks

Make sure to test your bookmarklet in different browsers and versions to ensure compatibility.
Use a secure protocol (HTTPS) to load your script to prevent CORS issues.
Use a proxy server to bypass CORB, but be aware that this can introduce additional latency and security risks.
Use the eval() function with caution, as it can execute malicious code.
Use the fetch() API with caution, as it can load data from a different origin, which can introduce security risks.

Frequently Asked Questions

Q: What is CORB? A: CORB is a security feature implemented in Chrome to prevent cross-origin resource sharing (CORS) attacks.
Q: Why is CORB blocking my script? A: CORB is blocking your script because it is loaded from a different origin, and Chrome's CORB feature prevents scripts from accessing data from other domains.
Q: How can I bypass CORB? A: You can bypass CORB using specific techniques, such as using the eval() function, using the fetch() API, or using a proxy server.

Conclusion

Introduction

In our previous article, we explored how to bypass Chrome's Cross-Origin Read Blocking (CORB) feature using a bookmarklet. However, we know that there are many questions and concerns about CORB and how to bypass it. In this article, we'll answer some of the most frequently asked questions about CORB and bypassing it.

Q: What is CORB?

A: CORB is a security feature implemented in Chrome to prevent cross-origin resource sharing (CORS) attacks. It blocks scripts from accessing data from other domains, even if the script is loaded from a different origin.

Q: Why is CORB blocking my script?

A: CORB is blocking your script because it is loaded from a different origin, and Chrome's CORB feature prevents scripts from accessing data from other domains. This is done to prevent malicious scripts from accessing sensitive data, such as cookies or local storage.

Q: How can I bypass CORB?

A: You can bypass CORB using specific techniques, such as using the eval() function, using the fetch() API, or using a proxy server. However, be aware that these techniques can introduce additional security risks and should be used with caution.

Q: What is the `eval()` function?

A: The eval() function is a built-in JavaScript function that can execute a string as JavaScript code. It can be used to bypass CORB by executing the script as a string, rather than loading it from a different origin.

Q: How do I use the `eval()` function to bypass CORB?

A: To use the eval() function to bypass CORB, you can use the following code:

javascript:(function(){var script=document.createElement('script');script.src='https://example.com/script.js';document.body.appendChild(script);eval(script.src);})();

Q: What is the `fetch()` API?

A: The fetch() API is a built-in JavaScript function that can load data from a different origin. It can be used to bypass CORB by loading the script from a different origin, rather than loading it from the same origin.

Q: How do I use the `fetch()` API to bypass CORB?

A: To use the fetch() API to bypass CORB, you can use the following code:

javascript:(function(){fetch('https://example.com/script.js').then(response=>response.text()).then(data=>eval(data));})();

Q: What is a proxy server?

A: A proxy server is a server that acts as an intermediary between the script and the web page. It can be used to bypass CORB by loading the script from a different origin, rather than loading it from the same origin.

Q: How do I use a proxy server to bypass CORB?

A: To use a proxy server to bypass CORB, you can use the following code:

javascript:(function(){var proxy='https://example.com/proxy.php';fetch(proxy+'?url=https://example.com/script.js').then(response=>response.text()).then(data=>eval(data));})();

Q: Are there any security risks associated with bypassing CORB?

A: Yes, there are security risks associated with bypassing CORB. Using the eval() function, the fetch() API, or a proxy server can introduce additional security risks, such as:

Cross-site scripting (XSS) attacks: Using the eval() function or the fetch() API can introduce XSS vulnerabilities, which can allow attackers to execute malicious code on the user's browser.
Cross-origin resource sharing (CORS) issues: Using a proxy server can introduce CORS issues, which can prevent the script from loading correctly.
Security risks associated with proxy servers: Using a proxy server can introduce security risks, such as man-in-the-middle attacks or data tampering.

Conclusion

In conclusion, bypassing Chrome's CORB feature can be a complex task, but it is possible using specific techniques. However, be aware that these techniques can introduce additional security risks and should be used with caution. Always test your bookmarklet in different browsers and versions to ensure compatibility, and use a secure protocol (HTTPS) to load your script to prevent CORS issues.